460 THE PRINCIPLES OF SCIENCE. 



judicious words in a despatch may irritate the national 

 pride ; the accidental discharge of a gun may precipitate 

 a collision, the effects of which will last for centuries. 

 It is said that the history of Europe at one moment 

 depended upon the question whether the look-out man 

 upon Nelson's vessel would or would not descry a ship 

 of Napoleon's expedition to Egypt which was passing 

 not far off. In human affairs, then, the smallest effects 

 may produce the greatest results, and in such circum- 

 stances the real application of scientific method is out 

 of the question. 



The Theory of Evolution. 



Very profound philosophers have lately generalized 

 concerning the production of living forms and the mental 

 and moral phenomena regarded as their highest develop- 

 ment. Mr. Herbert Spencer's Theory of Evolution pur- 

 ports to explain the origin of all specific differences, so 

 that not even the rise of a Homer or a Beethoven would 

 escape from his broad theories. The homogeneous is un- 

 stable and must differentiate itself, says Spencer, and hence 

 comes the variety of human institutions and characters. 

 In order that a living form shall continue to exist and 

 propagate its kind, says Mr. Darwin, it must be suitable 

 to its circumstances, and the most suitable forms will 

 prevail over and extirpate those which are less suitable. 

 From these fruitful ideas are developed theories of evo-j 

 lution and natural selection which go far towards ac- 

 counting for the existence of immense numbers of living 

 creatures plants, and animals. Apparent adaptations ofi 

 organs and limbs to useful purposes, which Paley and' 

 other theologicans regarded as distinct products of cre- 

 ative intelligence, are now seen to follow as natural 



